This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project is a companion to project 2039. These experiments were designed to elucidate factors that were contaminating the nuclear preps, as well as to test different nuclear prep methods. Whole cell and nuclear extracts from K562 and HepG2 were run in the FT-ICR (same column). This data suggests that the nuclear enrichments are void of most cytoplasmic proteins, but still contain mitochondrial membrane proteins. Additionally, a nuclear enrichment protocol that is commonly used in the literature was also tested for cytoplasmic contamination. This protocol gives a "cytoplasmic protein" fraction, a "nuclear protein" fraction and an insoluble pellet. This data suggests that the nuclear fraction obtained by this protocol contains a large amount of cytoplasmic proteins, and that the insoluble pellet contains a large number of nuclear proteins. Given the outcomes of this experiment, this nuclear protein protocol has been discarded from future use.